Burner control mechanism



April '9, 1946: s. G. ISSERSTEDT 2,393,008

BURNER CONTROL MECHANISM Filed .March 26, 1945 attorney I Patented 9,

. zseaoos PATENT? orrlCB I mm 'con'rnor'. measures! 7 Weir-midi,Toronto, Ontario, Canada,

a n-lgnor macaroni-Honeywell UNI-ran Regulator to.GompanLmnnegpolilJflnn-Jesrpontionof Delaware Application m es. 194:.Serial No. am;

DCla-imI- -(Cl.158--28') The present invention is concerned with burnercontrol mechanism and more particular y 'w mechanism oi the typedesigned to detect the Proper operation of the burner ignition meansignition means employing a single temperature responsive element todetect both the pr p r operation of the ignition means and also the eslotive to stop operation of the timer first if ignition has not beensuccessfully established and finally if combustion is not established.

A still further object of the invention is to provide a burner controlmechanism of the type set forth in the previous object in which thetemperature responsive element is a. thermocouple hot junction subjectedto the heat produced by the ignition means and also to that 5 I producedby the burner flame.

A still further object of the invention is to provide such a burnercontrol'me'chanism in which the thermocouple controls the energize-tionof one 1 winding of a relay, this winding being capable of holding therelay incapableof moving it to its energized position. A further objectof the invention is to provide a burner control mechanism in whichprovision is made for determining whether ignition has been successfullyestablished and in recycling if I it has not, with means for rendering asafety controller efiective to 'stopoperation oi the mechanism after aplurality of such unsuccessful attempts have been made.

Other objects of the invention will be apparent from a consideration oi!the appended specification, claims and drawing of which the singlefigure is a schematic illustration of my burner control mechanismembodied in a burner control,

Referring specifically to the drawing, an oil 7 burneris designated bythe reference numeral It. This oil burner is of a conventional designcomprising an'oil burner motor llhaving motor terminals I2 and IS. Themotor H operates in the conventional manner to operate a blower to forcean atomized mixture ofiuel and air-through a burner nozzle ll.Associated'with the oil burary winding of this ignition transformer isconnected through .conductors l1 and il to a pair of ignition electrodesII and II. These ignition electrodes II and II are eitective'whenthe-ignition transformerll atomized fuel mixture issulng irom'nozle II.

The operation of the burner is controlled by a main control switch whichisfillustratively shown in the form of a room thermostat 25. Thisthermostat comprises a bi-metallic element 20 to which is secured a pairof yieldable contact blades 21 and 20, adapted sequentially to engage apair of fixed contacts}! and 3|, respectively. Contact blade 21 andcontact 20 are less widely spaced from each other than are contact blade28 and contact II. Thus upon contact blades 21 and 28. being moved tothe leit as occurs upon a reduction in the temperature to whichbi-metallic element 26 is exposed. contact blade 21 engages with contact19 before contact blade 28 engages with relays ll and I. The relay I lcomprises a relay winding 42 and switch blades 43, I4, and I5 actuatedthereby. The switch blades 43, M, and 45 are adapted to engage fixedcontacts 46,11, and u. The switch blades 43 to ll and the contacts 48 toA8 are biased apart by any suitable means (not shown). 'Uponenergization oi relay winding 42, the switch blades 43 to 45 aremovedinto engagement with contacts 46 to II.

The relay ll comprises two windings I0 and I and a, pair of switchblades 2 and 58. The switch blades 52 and 53 are adapted to cooperatewith fixed contacts 54 and 55.. An armature it is associated with relaywinding BI and an-armature burner nozzle it in such a position that thehot ner is an ignitiomtransi'ormer II. The secondas junction is aiiectedby the heat or the burner is energized'to ignite theflame as wellas bythe heat of the spark existing between electrodes 18 and, 28 when theignition means is operating properly. Thearmature 51 is of a materialhaving a high permeability and the winding II as well as the conductors88 and 88 are of extreme y low resistance so as to utilize as fully aspossible the electromotive force generated by thermocouple 8!. Becauseof this, the winding 8! and armature 8'! are capable of holding switchblades 82 and 88 in engagement with contacts 54 and 88 after' they havebeenmoved into such engagement by the previous uperation of coil 88 andarmature 88. It is to be understood, however, that coil II and armature81 are incapable of moving the switch blades 82 and 88 into engagementwith contacts 84 and 85 but are merely capable of holding them insuchengagement after they have been moved. While the winding 8i and thearmature 81-have been shown as a solenoid winding and core in 'ordertosimplify the illustration, it is to be understood in a double helixbi-metallic element of the type disclosed in Parsons Patent 2,121,259,dated June 21,

1938. Such an element consists of a bi-metallic element wound in a formof a helix about a helical axis. Such an element, because of the largeamount of bi-metal and its particular disposition, operates when heatedto move in a straight line and to exert a substantial force in somoving.

Furthermore, because of the length of the element, its resistance isappreciable so that it is capable of being heated by the passage ofcurrent therethrough. ,As a result, no external heater is necessary. Theelement 84 is connected toa pair of switchblades 85 and 88 and a pair ofswitch actuating arms 88 and 18. The switch blades 85 and 88 cooperatewith contacts 81 and 88, respectively. Switch blade 85 is biased intoengagement with contact 81 while switch blade 88 is biased out ofengagement with contact 88. Upon the element 84 65 is moved out ofengagement with contact 81 and later switch blade 88 is moved intoengagement with contact 88. Switch actuating arms 88 and 18 are designedto cooperate with snap switches 12 and 13. Snap switches 12 and 13 eachcomprise a switch blade adapted to move with a snap actuation out ofengagement with one contact and into engagement with another contact ora fixed stop. ,The snap switch 12 comprises a switch arm 14 normally inengagement with a contact 15 and adapted to move into engagement with acontact 18. Associated with the arm is snap action mechanism (not shown)and a button 18. Upon the button 18 being pushed inwardly, the arm 14 ismoved with a snap action out of engagement with contact 15 and intoengagement with contact 18. The snap switch 13 comprises a switch blade"which is normally in engagement with contact 8| and a switch actuatingbutton 82 which upon being pressed inwardly causes the switch blade 88to be moved being heated so that the right I hand end thereof moves tothe left, switch blade with a snap action out of engagement contact 8iand into'engagement with a stop 83.

Thetwo snap switches 18 and 13 may take any conventional form, onedesirable form being that in the patent to Albert E. Baal: No.

2,318,734 dated my I1, 1943.

The switch blades 88 and 88 and the switch actuating arms 88 and 18 areso spaced with respect -to the associated contacts and the switchactusiting buttons 18 and 82, that upon the element 84 being heated,snap blade 85 is first-moved out of engagement with contact 8!, switchactuating arm 88 is next moved into engagement with switch actuatingbutton 18 to move switch blade 14 .out of engagement with contact 15 andinto engagement with contact 18, switch actuating arm 1|! isnext moved"into engagementgwith ly switch blade 88 contact 68.

The numerals I, 2, 3, and 4, enclosed 'in circles V have-been applied tothe 'drawingto indicate the order in which the various switch switchactuating arms are'actuated.

A thermal safety switch is designated by the reference numeral 88. Thiscomprises a pair of switch blades 88 and 81 which are biased apart butare held in engagement by a bi-metallic element 88. Associated with thebi-metallic element 88 is an electric heater 88. The bi-metallic element88 is so arranged that upon being heated by the heater 88, it warps tothe left so as to tend to move out of engagement with switch blade 81.If the heating continues until bi-metallic element 88 moves out ofengagement with switchblade 81, switch blade 81 moves away from switchblade 88 and it is necessary manually to reclose the switch blades. v

' Operation The various elements are shown in-the position that theyassume when which the thermostat 25 is responsive is at or above thedesired value so that there is no demand for burner operation. Now letit be assumed that this temperature drops so as to cause the sequentialengagement of contact blades 21 and 28 with contacts 28 and 38. Noenergizing circuit is established until both contact blades 21 and 28have engaged with contacts 28 and 80. When this happens, an energizingcircuit is established to relay winding 42 as follows: from theright-hand terminal, of secondary 33 through conductor 82, contact 28,contact blades 21 and 28, contact 38, conductors 83 and 84, contact 81,switch blade 85, conductor 88, heater 88, conductor 88, switch blades 81and 88, conductor 81, relay winding 42, and conductor 88-to the otherterminal of secondary 33; The establishment of this energizing circuitto relay coil 42 causes switch blades 43, 44, and 45 to be moved intoengagement with contacts 48, 41, and 48.

The engagement of switch blade 44 .with contact 41 establishes a holdingcircuit for relay winding 42 as follows: from the right hand terminal ofrelay winding 33 through conductor 82. contact 28, contact arm21,"bi-metallic element 26, conductor 99, switch blade 44, contact 41,conductor 84, contact 81, switch blade 85, conductor 85, heater '88,conductor 88, switch blades 81 and 88, conductor 81, relay winding 42and conductor 88 to the otherterminal of secondary 33. It is noted thatthe new circuit is independent of contact blade 28'and contact 80. Thus,

blades and the temperature to,

as the temperature rises, the apparatus is not placed out of operationuntil the temperature has risen suiiiciently to cause separation'ofcontact blade 21 from contact 29. This insures against chattering of therelay due to any rapid fluctuation in temperature or vibration of thethermostat.

The movement of switch blade 45 into engagement with contact 46 causes.the following energizing circuit to be established to relay winding 50:from line wire 31 through conductor IOI, contact 46, switch blade 46,conductors I02, I03, and I04, switch blade 14, contact 15, conductorI05, relay winding 50, and conductors I06, I01, I06, and I 09 back tothe other line wire 36. The energization of relay winding 50 causesswitch blades 52 and 53 to be moved into engagement with contacts 54 and55. The engagement of switch blade 52 with contact 54 establishes a newholding circuit to relay coil 42 as follows: from the right handterminal of secondary 33 through conductor 92, contact 29, contact blade21, bi-metallic element 26, conductor 99, switch blade 44, contact 41,conductor III, switch blade 43, contact 46, conductor 2, switch blade52, contact 54, conductors I I3 and 95, heater 69, conductor 96, switchblades 61 and 66, conductor 91, relay winding 42, and conductor 96 tothe other terminal of secondary 33. It will be noted that the newcircuit is independent of switch blade 65 and contact 61 of timingswitch 63. The original energizing circuits included this switch 65 andcon-. tact 61 so that it was necessary for timer 63 to be in its coldposition before the system could be placed into operation. It isdesirable, however, after this first check has been made to causeenergization of the relay 40 to be independent of the time switch sothat it will not be deenergized when the time switch begins to move thevarious switches associated with it upon being heated.

The movement of switch blade 45 into engagement with contact 46 alsoestablishes the following energizing circuit to the primary of theignition transformer I6: from line wire 31 through conductor IOI,contact 46, switch blade 45, conductors I02 and 5, contact 6|, switchblade 60; conductor 6, ignition transformer I6, and conductors H1 andI09 to the other line wire 36. The establishment of this energizingcircuit results in a spark being produced across the electrodes I9 and20 if the ignition means is functioning properly. If this spark isestablished, the spark begins to heat up the hot junction of. ther--mocouple 6 I.

The engagement of blade 45 with contact 46 also establishes thefollowing energizing circuit to bi-metallic element 64: from line wire31 through conductor contact 46, switch blade 45, conductors I02, I03,and H9, bi-metallic element 64, and conductors I20, I01, I06, and I06back to the other line wire 36. The establishment of this energizingcircuit to bimetallic element 64 causes the latter to begin to heat soas to move switchblades 65, 66, and switch actuating arms 69 and '10towards the left. As previously explained, the first element to be movedis switch blade 65 which moves out of engagement with contact 61 andthus interrupts the original energizing and holding circuits to relaywinding 42. Since, however, a new holding. circuit has been establishedas described above, relay coil 42 remains energized 'despite theseparation of switch blade 65 from contact 61. After a predetermined.period of time suflicient for the thermocouple 6| to be heated by theignition spark if the ignition ing it to be deenergized. Thedeenergization of relay coil 42 will in turn result in the bi-metallicelement 64 of timer 63 and-the ignition transformer I6 beingdeenergized. Since relay coil 42 cannot be reenergized until the timer63 has moved back to its cold position so as to reengage switch blades65 with contact 61, it is necessary for the system 0t recyclecompletely.

If, however, the ignition means operates properly, relay 4| will remainin its energized position holding switch blade 53 in engagement withcontact 55. Under these conditions, the engagement of switch blade 14with contact 16 will cause the following energizing circuit to beestablished to burner motor II: from line wire 31 through conductor |0I,contact 40, switch blade 45, conductors I02, I03, and I04, switch blade14, contact 16, conductor I23, contact 56, switch blade 63, conductorI24, motor terminals I2 and I3, and conductors I25, I06, and I09 back tothe other line winding 36. The establishment of this circuit results inthe establishment of all the conditions necessary to combustion takingplace. Under normal conditions, since-the proper operation of theignition means has already been checked, the atomized fuel mixtureissuing from nozzle will be ignited by the spark between electrodes I9and 20.

At the end of a predetermined period of time after switch actuating arm69 has actuated switch blade 14, switch actuating arm 10 is effective toactuate switch blade 60. Upon switch actuating I arm 10 being moved tothe left into engagement with button 62, as previously explained, switchblade is moved with a. snap action out of engagement with contact 6|.When this happens, the circuit previously traced to the ignitiontransformer I6 is interrupted. The period of time between the actuationof switch blades 14 and 60 is normally sufficient to permit combustionto be properly established. Thus, in spite of the ignition beingdeenergized, the thermocouple 6| remains heated because of the presenceof the burngized position and thermal element 64 continues to heat. I

After a further predetermined period of time,

switch blade 66 of timer 63 is moved into engagement with contact 66,establishing the following new circuit to relay coil 42: from the righthand terminal of secondary 33 through a conductor 92, contact 29,contact blade 21, bimetallic element 26, conductor 99, switch blade 44,conductor 41, conductor III, switch blade 43, contact 46, conductor II2, switch blade 52, contact 54, conductors H3, and I26, switch blade66, contact 66, conductor I29, contact blades 81 and 66, conductor 61,relay coil 42, and conductor 96 to the other terminal of secondary 33.It will be noted that the new circuit does not include the safety switchheater 69. Theestablishment of this circuit shorts out the safety switchheater so as to terminate its heating eifect. The timing of time switch63 is sumcient that this entire means is functioning satisfactorily,switch actu-.

sec' uence takes place before the bi-metallic element '88 has becomeheated suiiiciently to move from out of engagement with switch blade 81.Hence, the system continue in operation until thermostat 25 issatisfied.

Whenever the temperature of the medium to which bi-metallic element 28is responsive has risen sufliciently to cause separation of contactblade 21 from contact 29, all of the circuits traced to relay coil 42will be interrupted so as to terminate energization of the burner motorII, the timer 83, and relay 4|.

The system cannot be again placed into operation until the temperaturehas dropped sufliciently to cause reengagement of contact blades 21 and28 with contacts 28 and 80 and until the timer 88 has been allowed tocool suiliciently to reengage switch blade 85 with contact 81 whichoccurs only after switch blade 68 and switch actuating armatures 68 and18 have again assumed the position shown'in the drawing. Thus, it isassured that adequate time will be provided for the thermocouple 6| tocool off before the apparatus is again placed in operation.

Operation if combustion is not initially established It will be notedfrom the preceding description that when the switch blade 14 dlsengagesfrom contact 15 to deenergize relay coil 50 and later when switch blade88 disengages from contact 8| to deenergize the ignition, the relay 4|moves to its deenergized position unless the mechanism is properlyoperating. In the first case, the proper operation involves the properoperation of the ignition means. In the second case, it involves theestablishment of combustion. In either case, the movement of relay 4| todeenergized position causes deenergization of relay 48 and timer 83 andstops all operation of the system until switch blade 65 of timer 83reengages contact 61. If at this time, both the thermostat contactblades 21 and "are in engagement with contacts 29 and 30, theiicycle isstarted over again. While the heater 88 is deenergized during the timethat relay 4!) is deenergized, while the timer is cooling it will beobvious that when the system recycles, heater 89 will still retain acertain amount of heat. Thus, if the system again fails to operateproperly, bi-metallic element 88 wil1 be at a higher temperature than atthe beginning of the first attempt to start operation of the system.Depending upon the relative timing of timer 63 and safety switch 85, thebi-metallic element 88 may be made to disengage the safety switch blade81 and shut down the system after two or more attempts to start. It willthus be seen if combustion is not successfully established at first, oneor more further attempts will be made to establish combustion. If theseattempts are likewise unsuccessful, the-cumulative heating ofbi-metallic element 88 by heater 89 will cause the safety switch to opento shut down the system until the safety switch is manually reclosed.

Operation in case of combustion failure timer 63. It is not possible forthe system to again be placed into operation until timer 83 cools downto a point where the various switch 7 blades again resume their coldpositions, as in the drawing. This timing period is 'sufllcient for thethermocouple to cool and for any unburned gases in the furnace to passout throu h the stack. If, at this time, both thermostat blades 21 and'28 are in engagement with their associated contacts 29 and 30, theoperation first described will be repeated. If this attempt isunsuccessful, the cycle will be repeated. In other words, a series ofattempts will be made to restart the system and if these attempts areun-' successful, the safety switch will be opened so as to shut down thesystem awaiting manual intervention.

vConclusion It will be seen that I have provided a burner controlmechanism employing a single element to detect both the proper operationof an actuating means and also the establishment of combustion. It willfurther be seen that this burner control mechanism provides for safeoperation in the event of any possible type of abnormal operation.

While I have shown a specific embodiment of my invention, it is to beunderstood that this is for purposes of illustration and that myinvention is limited only in scope by the appended claims.

I claim as my invention:

1. In control apparatus for a fuel burner con trol motor and ignitionmeans; a safety controller for interrupting operation of said apparatusat the end of'a timed period; a timer, means including said timer forestablishing circuit connections adapted to lead to said motor means,

then interrupting circuit connections adapted to control energization ofsaid ignition means, and finally rendering said safety controllerinoperative, means adapted to respond to a condition indicative both ofthe proper operation of the ignition means and of the presence ofcombustion, and means including said last named means adapted tocontinue operation of said timer after the circuit connections for saidignition means have been interrupted only if said condition responsivemeans indicates the maintenance of said condition due to theestablishment of combustion.

2. In control apparatus for a fuel burner con} trol motor and ignitionmeans, a safety controller for interrupting operation of said apparatusat the end of a timed period, a timer, means including said timer forestablishing circuit connections adapted to lead to said motor means,then interrupting circuit connections adapted to control energization ofsaid ignition means, and

finally rendering said safety controller inopera-' tive, a temperatureresponsive element adapted to be located so as to be subjected to theheat produced both by the ignition means and by combustion, and meansincluding said temperature responsive element adapted to continueoperation of said timer after the circuit connections for said ignitionmeans have been interrupted only if said temperature responsive elementcontinues to be heated as the result of the establishment of combustion.4

3. In control apparatus for a fuel burner control motor and ignitionmeans, a safety controller for interrupting operation of said. apparatusat the end of a timed period, a timer, meansninclud-. ing said timer forfirst establishingpircuii; conascaoos said timer only if the ignitionmeans is functionlng properly and later after the ignition means hasbeen deenergized to continue operation of said timer only if combustionhas been established.

4. In control apparatus for a fuel burner control motor and ignitionmeans; a safety controller for interrupting operation of said apparatusat the end of a timed period, a timer, means including said timer forfirst establishing circuit connections adapted to lead to said ignitionmeans, then after a first timed period establishing circuit connectionsadapted to lead to said motor means, then interrupting said circuitconnections for said ignition mean's aftera further timed period andfinally rendering s'aid safety controller inoperative, a temperatureresponsive element adapted to be located so as to be subjected to theheat produced both by the ignition means and by combustion. and meansincluding said temperature responsive element adapted to interruptoperation of said timer before said circuit connections for said motorare establishedif said temperature responsive element is not heated bysaid ignition means and later to interrupt operation of said timer aftersaid ignition circuit conhas not been established.

5. In a fuel burner, control system, a burner, ignition means therefor,a thermocouple having its hot junction located so as to be heated eitherby the heat produced by the ignition means or by that produced by theflame of the burner,

tion of said ignition means after the end of a second timed periodindependently of said winding to cause termination of the operation ofsaid burner and said timer if said winding does not remain energizedbecause of the thermocouple being heated by the fiame of the burner.

6. In control apparatus for a fuel burner motor and ignition means; atemperature responsive element adjacent said ignition means and exposedto the heat thereof; a time switch including an electrically energizedtimer and first and main in energized position independently of saidfirst circuit means upon said temperature responsive element beingheated by said ignition means; further circuit means adapted to causeenergization of said burner motor upon closure of both said second andthird switches; said timer being operative a period of time afterclosure of said main switch to open said first switch and terminateenergization of said relay by said first circuit means and to close saidsecond switch to cause energization of said burner motor by said Ifurther circuit means if said relay remains ,in energized positionfollowing the opening of said first switch.

7. In control apparatus for a fuel burner motor and ignition means; athermocouple having its hot junction adjacent said ignition means andexposed to the heat thereof; a time switch inf cluding an electricallyenergized timer and first nections have been interrupted if combustion?second switches; a relay comprising a third switch closed when saidrelay is energized; a main control switch; a first circuit means adaptedupon closure of said main switch to cause energization of said timer,said relay and the ignition means; second circuit means including saidtemperature responsive element for causing said relay to reand secondswitches; a relay comprising a plurality of windings and a third switch,said third switch being closed when either one of said windings isenergized; a main control switch; a first circuit means adapted uponclosure of said main switch to cause energization of said timer, a firstof said relay windings, and the ignition means: connections between theother of said relay windings and said thermocouple for causing saidrelay to remain in energized position independently of said firstcircuit means upon the hot junction of said thermocouple being heated bysaidignition means; further circuit means adapted to cause energizationof said burner motor upon closure of both said second and thirdswitches; said timer being operative a period of time after closure ofsaid main switch to open said first switch and terminate energization ofsaid. one relay winding by said first circuit means and to close saidsecond switch to cause energization of said burner motor by said furthercircuit means if said relay remains in energized position following theopening.

burner operation first to initiate operation of said ignition means,then to terminate operation of said ignition means and said timer aftera first timed period if said temperature responsive element has not beenheated by said ignition means, and finally to terminate operation ofsaid ignition means at the end of a second timed period independently ofsaid temperature responsive element to cause termination of theoperation of said burner and said timer if said temperature responsiveelement is not maintained hot by the flame of the burner.

9. In control apparatus for a burner fuel control motor and ignitionmeans; a time switch including an electrically energized timer andswitch means operated thereby, said timer moving in one direction whenenergized and in an opposite direction when deenergized; a first relayadapted to control the energization of said timer, saidfuel controlmotor, and said ignition means; circuit connections controlled by saidtime switch and ignition means is functioning properly or combustion isestablished; and means controlled by said time switch and operative tocause deenergizetion or said ignition means a predetermined period ortime aiter energization oi said timer so that said second relay becomesdeenergized if combustion has not then been established.

ISSERSTEDT.

